SpikeShaper is a Windows program for exploring and fitting parameters to Hodgkin-Huxley-type single compartment neural models. It provides an off-the-shelf generalised HH simulator that allows rapid construction of models, and easy exploration of the effects of changing the ionic and kinetic properties of models. The programme also provides a facility for fitting the parameters of such models to template waveforms.
The graphical display shows a standard Hodgkin-Huxley spike generated by the default model. On the left is a dockable property sheet that defines the model. The Main (active) tab defines the stimulus and the passive properties of the model, and controls the fit-to-template process. The non-active tabs (HH-Na and HH-K) define the properties of the individual ion channels.
A screenshot of the SpikeShaper start-up display.
The standard HH model contains just two channel types, but the user can add as many channels as he/she wishes, or modify the existing channels. Each channel can have kinetics defined by built-in or user-supplied equations. This enables the user to replicate many aspects of neural models published in the literature.
Simulation of an inking motorneurone implemented with user-defined equations (parameters from Byrne 1980, J. Neurophysiol, 43:651-668). Traces (top to bottom) are volage, stimulus current, A-current conductance.
The user first loads a template file containing the spike waveform generated by the target system. The user constructs a model which contains the channel types which are thought to be present in the target system, and identifies which parameters can be varied in attempting to achieve a fit, and the acceptable limits of those parameters. SpikeShaper uses simulated annealing to try to find the parameter set which generates the simulated waveform most closely matching the template waveform.
The template waveform is shown in purple, the current model waveform in black. The current model is an HH model, but with increased membrane capacitance and leakage conductance, and decreased leakage equilibrium potential. The programme will adjust these parameters to attempt to match the model waveform to the template waveform between the vertical cursors.
SpikeShaper is free software. To obtain the program:
Please note that SpikeShaper comes with no guarantees whatsoever, and although considerable effort has been made to ensure that it works correctly, you use it at your own risk.
SpikeShaper version 1.0.9, released July 2007.
Please send bug reports and/or comments to the author.